Comprehensive LC-MS/MS Analysis of Nitrogen-Related Plant Metabolites

We have developed and validated a novel LC-MS/MS method for simultaneously analyzing amino acids, biogenic amines, and their acetylated and methylated derivatives in plants. This method involves a one-step extraction of 2-5 mg of lyophilized plant material followed by fractionation of different biogenic amine forms and exploits an efficient combination of hydrophilic interaction chromatography (HILIC), reversed phase (RP) chromatography with pre-column derivatization, and tandem mass spectrometry. This approach enables high-throughput processing of plant samples, significantly reducing the time needed for analysis and its cost. We also present a new synthetic route for deuterium-labelled polyamines. The LC-MS/MS method was rigorously validated by quantifying levels of nitrogen-related metabolites in seedlings of seven plant species including Arabidopsis, maize, and barley, all of which are commonly used model organisms in plant science research. Our results revealed substantial variations in the abundance of these metabolites between species, developmental stages, and growth conditions, particularly for the acetylated and methylated derivatives and the various polyamine fractions. However, the biological relevance of these plant metabolites is currently unclear. Overall, this work contributes significantly to the field of plant science by providing a powerful analytical tool and setting the stage for future investigations into the functions of these nitrogen-related metabolites in plants.

13C-labeling reveals non-conventional pathways providing carbon for hydroxy fatty acid synthesis in Physaria fendleri

Physaria fendleri is a member of the Brassicaceae that produces in its embryos hydroxy fatty acids, constituents of oils that are very valuable and widely used by industry for cosmetics, lubricants, biofuels, etc. Free of toxins and rich in hydroxy fatty acids, Physaria provides a promising alternative to imported castor oil and is on the verge of being commercialized. This study aims to identify important biochemical step(s) for oil synthesis in Physaria, which may serve as target(s) for future crop improvement. To advance towards this goal, the endosperm composition was analysed by LC-MS/MS to develop and validate culture conditions that mimic the development of the embryos in planta. Using developing Physaria embryos in culture and 13C-labeling, our studies revealed that: (i) Physaria embryos metabolize carbon into biomass with an efficiency significantly lower than other photosynthetic embryos; (ii) the plastidic malic enzyme provides 42% of the pyruvate used for de novo fatty acid synthesis, which is the highest measured so far in developing 'green' oilseed embryos; and (iii) Physaria uses non-conventional pathways to channel carbon into oil, namely the Rubisco shunt, which fixes CO2 released in the plastid, and the reversibility of isocitrate dehydrogenase, which provides additional carbon for fatty acid elongation.

Multifunctional 5-hydroxyconiferaldehyde O-methyltransferases (CAldOMTs) in plant metabolism

Lignin, flavonoids, melatonin, and stilbenes are plant specialized metabolites with diverse physiological and biological functions, supporting plant growth and conferring stress resistance. Their biosynthesis requires O-methylations catalyzed by 5-hydroxyconiferaldehyde O-methyltransferase (CAldOMT; also called caffeic acid O-methyltransferase, COMT). CAldOMT was first known for its roles in syringyl (S) lignin biosynthesis in angiosperm cell walls and later found to be multifunctional. This enzyme also catalyzes O-methylations in flavonoid, melatonin, and stilbene biosynthetic pathways. Phylogenetic analysis indicated the convergent evolution of enzymes with OMT activities towards the monolignol biosynthetic pathway intermediates in some gymnosperm species that lack S-lignin and Selaginella moellendorffii, a lycophyte which produces S-lignin. Furthermore, neofunctionalization of CAldOMTs occurred repeatedly during evolution, generating unique O-methyltransferases (OMTs) with novel catalytic activities and/or accepting novel substrates, including lignans, 1,2,3-trihydroxybenzene, and phenylpropenes. This review summarizes multiple aspects of CAldOMTs and their related proteins in plant metabolism and discusses their evolution, molecular mechanism, and roles in biorefineries, agriculture, and synthetic biology.

Methylation and Demethylation of Emerging Contaminants in Plants

Many contaminants of emerging concern (CECs) have reactive functional groups and may readily undergo biotransformations, such as methylation and demethylation. These transformations have been reported to occur during human metabolism and wastewater treatment, leading to the propagation of CECs. When treated wastewater and biosolids are used in agriculture, CECs and their transformation products (TPs) are introduced into soil-plant systems. However, little is known about whether transformation cycles, such as methylation and demethylation, take place in higher plants and hence affect the fate of CECs in terrestrial ecosystems. In this study, we explored the interconversion between four common CECs (acetaminophen, diazepam, methylparaben, and naproxen) and their methylated or demethylated TPs in Arabidopsis thaliana cells and whole wheat seedlings. The methylation-demethylation cycle occurred in both plant models with demethylation generally taking place at a greater degree than methylation. The transformation rate of demethylation or methylation was dependent on the bond strength of R-CH3, with demethylation of methylparaben or methylation of acetaminophen being more pronounced. Although not explored in this study, these interconversions may exert influences on the behavior and biological activity of CECs, particularly in terrestrial ecosystems. The study findings demonstrated the prevalence of transformation cycles between CECs and their methylated or demethylated TPs in higher plants, contributing to a more complete understanding of risks of CECs in the human-wastewater-soil-plant continuum.

MFP1 defines the subchloroplast location of starch granule initiation

Starch is one of the major carbohydrate storage compounds in plants. The biogenesis of starch granules starts with the formation of initials, which subsequently expand into granules. Several coiled-coil domain-containing proteins have been previously implicated with the initiation process, but the mechanisms by which they act remain largely elusive. Here, we demonstrate that one of these proteins, the thylakoid-associated MAR-BINDING FILAMENT-LIKE PROTEIN 1 (MFP1), specifically determines the subchloroplast location of initial formation. The expression of MFP1 variants "mis"-targeted to specific locations within chloroplasts in Arabidopsis results in distinctive shifts in not only how many but also where starch granules are formed. Importantly, "re" localizing MFP1 to the stromal face of the chloroplast's inner envelope is sufficient to generate starch granules in this aberrant position. These findings provide compelling evidence that a single protein MFP1 possesses the capacity to direct the initiation and biosynthesis machinery of starch granules.

CeO2NP priming enhances the seed vigor of alfalfa (Medicago sativa) under salt stress

Soil salinization is a common environmental problem that seriously threatens crop yield and food security, especially through its impact on seed germination. Nanoparticle priming, an emerging seed treatment method, is receiving increasing attention in improving crop yield and stress resistance. This study used alfalfa seeds as materials to explore the potential benefits of cerium oxide nanoparticle (CeO2NP) priming to promote seed germination and improve salt tolerance. CeO2NPs at concentrations up to 500 mg/L were able to significantly alleviate salt stress in alfalfa seeds (200 mM), with 50 mg/L of CeO2NP having the best effect, significantly (P< 0.05) increasing germination potential (from 4.0% to 51.3%), germination rate (from 10.0% to 62.7%), root length (from 8.3 cm to 23.1 cm), and seedling length (from 9.8 cm to 13.7 cm). Priming treatment significantly (P< 0.05) increased seed water absorption by removing seed hardness and also reducing abscisic acid and jasmonic acid contents to relieve seed dormancy. CeO2NP priming increased α-amylase activity and osmoregulatory substance level, decreased reactive oxygen species and malonaldehyde contents and relative conductivity, and increased catalase enzyme activity. Seed priming regulated carotenoid, zeatin, and plant hormone signal transduction pathways, among other metabolic pathways, while CeO2NP priming additionally promoted the enrichment of α-linolenic acid and diterpenoid hormone metabolic pathways under salt stress. In addition, CeO2NPs enhanced α-amylase activity (by 6.55%) in vitro. The optimal tested concentration (50 mg/L) of CeO2NPs was able to improve the seed vigor, enhance the activity of α-amylase, regulate the osmotic level and endogenous hormone levels, and improve the salt tolerance of alfalfa seeds. This study demonstrates the efficacy of a simple seed treatment strategy that can improve crop stress resistance, which is of great importance for reducing agricultural costs and promoting sustainable agricultural development.

An Arabidopsis mutant line lacking the mitochondrial calcium transport regulator MICU shows an altered metabolite profile

Plant metabolism is constantly changing and requires input signals for efficient regulation. The mitochondrial calcium uniporter (MCU) couples organellar and cytoplasmic calcium oscillations leading to oxidative metabolism regulation in a vast array of species. In Arabidopsis thaliana, genetic deletion of AtMICU leads to altered mitochondrial calcium handling and ultrastructure. Here we aimed to further assess the consequences upon genetic deletion of AtMICU. Our results confirm that AtMICU safeguards intracellular calcium transport associated with carbohydrate, amino acid, and phytol metabolism modifications. The implications of such alterations are discussed.

Structural analysis and molecular substrate recognition properties of Arabidopsis thaliana ornithine transcarbamylase, the molecular target of phaseolotoxin produced by Pseudomonas syringae

Halo blight is a plant disease that leads to a significant decrease in the yield of common bean crops and kiwi fruits. The infection is caused by Pseudomonas syringae pathovars that produce phaseolotoxin, an antimetabolite which targets arginine metabolism, particularly by inhibition of ornithine transcarbamylase (OTC). OTC is responsible for production of citrulline from ornithine and carbamoyl phosphate. Here we present the first crystal structures of the plant OTC from Arabidopsis thaliana (AtOTC). Structural analysis of AtOTC complexed with ornithine and carbamoyl phosphate reveals that OTC undergoes a significant structural transition when ornithine enters the active site, from the opened to the closed state. In this study we discuss the mode of OTC inhibition by phaseolotoxin, which seems to be able to act only on the fully opened active site. Once the toxin is proteolytically cleaved, it mimics the reaction transition state analogue to fit inside the fully closed active site of OTC. Additionally, we indicate the differences around the gate loop region which rationally explain the resistance of some bacterial OTCs to phaseolotoxin.

Meloidogyne enterolobii MeMSP1 effector targets the glutathione-S-transferase phi GSTF family in Arabidopsis to manipulate host metabolism and promote nematode parasitism

Meloidogyne enterolobii is an emerging root-knot nematode species that overcomes most of the nematode resistance genes in crops. Nematode effector proteins secreted in planta are key elements in the molecular dialogue of parasitism. Here, we show the MeMSP1 effector is secreted into giant cells and promotes M. enterolobii parasitism. Using co-immunoprecipitation and bimolecular fluorescent complementation assays, we identified glutathione-S-transferase phi GSTFs as host targets of the MeMSP1 effector. This protein family plays important roles in plant responses to abiotic and biotic stresses. We demonstrate that MeMSP1 interacts with all Arabidopsis GSTF. Moreover, we confirmed that the N-terminal region of AtGSTF9 is critical for its interaction, and atgstf9 mutant lines are more susceptible to root-knot nematode infection. Combined transcriptome and metabolome analyses showed that MeMSP1 affects the metabolic pathways of Arabidopsis thaliana, resulting in the accumulation of amino acids, nucleic acids, and their metabolites, and organic acids and the downregulation of flavonoids. Our study has shed light on a novel effector mechanism that targets plant metabolism, reducing the production of plant defence-related compounds while favouring the accumulation of metabolites beneficial to the nematode, and thereby promoting parasitism.

Uptake and metabolization of four sartan drugs by eight different plants: Targeted and untargeted analyses by HPLC-drift-tube-ion-mobility quadrupole time-of-flight mass spectrometry

In this study, we investigated the uptake and metabolization of four drugs (plus the associated prodrugs) from the sartan family by eight edible plants. Growing the plants hydroponically in a medium containing the respective drug, more than 40 phases I and II metabolites derived from the four sartan drugs could be tentatively identified. To demonstrate the suitability of the proposed analytical approach for actual environmental samples, garden cress (Lepidium sativum) selected as a model plant was grown in water drawn from the effluent of two local wastewater treatment plants. Thereby, three of the sartans, namely, olmesartan, candesartan, and valsartan, could be found in the plant extracts at concentrations of 3.1, 10.4, and 14.4 ng g-1 , respectively. Additionally, for candesartan and valsartan, a glycosylated transformation product could be detected. In order to extend the present (targeted) workflow also toward the analysis of unknown transformation products (i.e., those not listed in the custom-made database used for this research), a nontargeted approach for the analysis of plant extracts with respect to the presence of drug-related metabolites was developed. Comparison of the targeted and the nontargeted workflows led to the finding of two additional, so far unidentified, transformation products originating from azilsartan.

The Role of TCA Cycle Enzymes in Plants

As one of the iconic pathways in plant metabolism, the tricarboxylic acid (TCA) cycle is commonly thought to not only be responsible for the oxidization of respiratory substrate to drive ATP synthesis but also provide carbon skeletons to anabolic processes and contribute to carbon-nitrogen interaction and biotic stress responses. The functions of the TCA cycle enzymes are characterized by a saturation transgenesis approach, whereby the constituent expression of proteins is knocked out or reduced in order to investigate their function in vivo. The alteration of TCA cycle enzyme expression results in changed plant growth and photosynthesis under controlled conditions. Moreover, improvements in plant performance and postharvest properties are reported by overexpression of either endogenous forms or heterologous genes of a number of the enzymes. Given the importance of the TCA cycle in plant metabolism regulation, here, the function of each enzyme and its roles in different tissues are discussed. This article additionally highlights the recent finding that the plant TCA cycle, like that of mammals and microbes, dynamically assembles functional substrate channels or metabolons and discusses the implications of this finding to the current understanding of the metabolic regulation of the plant TCA cycle.

Characterization of Arabidopsis thaliana Coq9 in the CoQ Biosynthetic Pathway

Coenzyme Q, also known as ubiquinone, is a fat-soluble isoprene quinone that serves as a cofactor for numerous enzymes across all domains of life. However, the biosynthetic pathway for this important molecule in plants has been examined in only a limited number of studies. In yeast and mammals, Coq9, an isoprenoid-lipid-binding protein, is essential for CoQ biosynthesis. Previous studies showed that Arabidopsis thaliana Coq9 failed to complement the fission yeast Schizosaccharomyces pombe coq9 null mutant, and its function in plants remains unknown. In this study, we demonstrated that expression of Arabidopsis Coq9 rescued the growth of a yeast temperature-sensitive coq9 mutant and increased CoQ content. Phylogenetic analysis revealed that Coq9 is widely present in green plants. Green fluorescent protein (GFP) fusion experiments showed that Arabidopsis Coq9 is targeted to mitochondria. Disruption of the Coq9 gene in Arabidopsis results in lower amounts of CoQ. Our work suggests that plant Coq9 is required for efficient CoQ biosynthesis. These findings provide new insights into the evolution of CoQ biosynthesis in plants. The identification of Coq9 as a key player in CoQ biosynthesis in plants opens up new avenues for understanding the regulation of this important metabolic pathway.

Manipulation of plant metabolism by pathogen effectors: more than just food

To successfully infect plants, pathogens secrete effector proteins to the plant apoplast or inside plant cells, where they suppress plant immunity or interfere with other cellular processes to facilitate infection. Plant metabolism is crucial for most cellular processes and plays a key role in defense against pathogens, making it a major target for pathogen effectors. Effector proteins manipulate host metabolism to provide the pathogen with nutrients or to indirectly suppress plant chemical defense responses. Recent studies have shown that pathogens also utilize effectors to shape the microbiota composition by altering the concentration of certain plant metabolites. Here, we summarize current knowledge on the manipulation of plant metabolism by pathogen effectors. We also discuss what remains unknown regarding the manipulation of host metabolism by pathogen effectors.

Promiscuity, a Driver of Plant Cytochrome P450 Evolution?

Plant cytochrome P450 monooxygenases were long considered to be highly substrate-specific, regioselective and stereoselective enzymes, in this respect differing from their animal counterparts. The functional data that have recently accumulated clearly counter this initial dogma. Highly promiscuous P450 enzymes have now been reported, mainly in terpenoid pathways with functions in plant adaptation, but also some very versatile xenobiotic/herbicide metabolizers. An overlap and predictable interference between endogenous and herbicide metabolism are starting to emerge. Both substrate preference and permissiveness vary between plant P450 families, with high promiscuity seemingly favoring retention of gene duplicates and evolutionary blooms. Yet significant promiscuity can also be observed in the families under high negative selection and with essential functions, usually enhanced after gene duplication. The strategies so far implemented, to systematically explore P450 catalytic capacity, are described and discussed.

Salicylic acid had the potential to enhance tolerance in horticultural crops against abiotic stress

Horticultural crops are greatly disturbed by severe abiotic stress conditions. This is considered one of the major threats to the healthy lives of the human population. Salicylic acid (SA) is famous as one of the multifunctional phytohormones that are widely found in plants. It is also an important bio-stimulator involved in the regulation of growth and the developmental stages of horticultural crops. The productivity of horticultural crops has been improved with the supplemental use of even small amounts of SA. It has good capability to reduce oxidative injuries that occur from the over-production of reactive oxygen species (ROS), potentially elevated photosynthesis, chlorophyll pigments, and stomatal regulation. Physiological and biochemical processes have revealed that SA enhances signaling molecules, enzymatic and non-enzymatic antioxidants, osmolytes, and secondary metabolites activities within the cell compartments of plants. Numerous genomic approaches have also explored that SA regulates transcriptions profiling, transcriptional apprehensions, genomic expression, and metabolism of stress-related genes. Many plant biologists have been working on SA and its functioning in plants; however, its involvement in the enhancement of tolerance against abiotic stress in horticultural crops is still unidentified and needs more attention. Therefore, the current review is focused on a detailed exploration of SA in physiological and biochemical processes in horticultural crops subjected to abiotic stress. The current information is comprehensive and aims to be more supportive of the development of higher-yielding germplasm against abiotic stress.

Genetic and epigenetic control of the plant metabolome

Plant metabolites are mainly produced through chemical reactions catalysed by enzymes encoded in the genome. Mutations in enzyme-encoding or transcription factor-encoding genes can alter the metabolome by changing the enzyme's catalytic activity or abundance, respectively. Insertion of transposable elements into non-coding regions has also been reported to affect transcription and ultimately metabolite content. In addition to genetic mutations, transgenerational epigenetic variations have also been found to affect metabolic content by controlling the transcription of metabolism-related genes. However, the majority of cases reported so far, in which epigenetic mechanisms are associated with metabolism, are non-transgenerational, and are triggered by developmental signals or environmental stress. Although, accumulating research has provided evidence of strong genetic control of the metabolome, epigenetic control has been largely untouched. Here, we provide a review of the genetic and epigenetic control of metabolism with a focus on epigenetics. We discuss both transgenerational and non-transgenerational epigenetic marks regulating metabolism as well as prospects of the field of metabolic control where intricate interactions between genetics and epigenetics are involved.

Phylogenomic analyses across land plants reveals motifs and coexpression patterns useful for functional prediction in the BAHD acyltransferase family

The BAHD acyltransferase family is one of the largest enzyme families in flowering plants, containing dozens to hundreds of genes in individual genomes. Highly prevalent in angiosperm genomes, members of this family contribute to several pathways in primary and specialized metabolism. In this study, we performed a phylogenomic analysis of the family using 52 genomes across the plant kingdom to gain deeper insights into its functional evolution and enable function prediction. We found that BAHD expansion in land plants was associated with significant changes in various gene features. Using pre-defined BAHD clades, we identified clade expansions in different plant groups. In some groups, these expansions coincided with the prominence of metabolite classes such as anthocyanins (flowering plants) and hydroxycinnamic acid amides (monocots). Clade-wise motif-enrichment analysis revealed that some clades have novel motifs fixed on either the acceptor or the donor side, potentially reflecting historical routes of functional evolution. Co-expression analysis in rice and Arabidopsis further identified BAHDs with similar expression patterns, however, most co-expressed BAHDs belonged to different clades. Comparing BAHD paralogs, we found that gene expression diverges rapidly after duplication, suggesting that sub/neo-functionalization of duplicate genes occurs quickly via expression diversification. Analyzing co-expression patterns in Arabidopsis in conjunction with orthology-based substrate class predictions and metabolic pathway models led to the recovery of metabolic processes of most of the already-characterized BAHDs as well as definition of novel functional predictions for some uncharacterized BAHDs. Overall, this study provides new insights into the evolution of BAHD acyltransferases and sets up a foundation for their functional characterization.

Metabolite Signature and Differential Expression of Genes in Washington Navel Oranges (Citrus sinensis) Infected by Spiroplasma citri

Spiroplasma citri is the pathogen that causes citrus stubborn disease (CSD). Infection of citrus with S. citri has been shown to cause leaf mottling, reduce fruit yield, and stunt tree growth. Fruit from trees exhibiting symptoms of CSD are misshapen and discolored. The symptoms of CSD are easily confused with nutrient deficiencies or symptoms of citrus greening disease. In this study, young Washington navel oranges (Citrus sinensis) were graft-inoculated with budwood originating from trees confirmed to be infected with S. citri. Leaf samples were collected monthly for 10 months for metabolomics and differential gene expression analyses. Significant differences in the concentration of metabolites and expressed genes were observed between control and S. citri-infected trees throughout the experiment. Metabolites and genes associated with important defense and stress pathways, including jasmonic acid signaling, cell wall modification, amino acid biosynthesis, and the production of antioxidant and antimicrobial secondary metabolites, were impacted by S. citri throughout the study, and even prior to symptom development. This work fills a current gap in knowledge surrounding the pathogenicity of S. citri and provides an updated mechanistic explanation for the development of CSD symptoms in S. citri-infected plants.

Linkages between Sphagnum metabolites and peatland CO2 uptake are sensitive to seasonality in warming trends

Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake. We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP). When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn. Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming-induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change.

Effect of Duration of LED Lighting on Growth, Photosynthesis and Respiration in Lettuce

Parameters of illumination including the spectra, intensity, and photoperiod play an important role in the cultivation of plants under greenhouse conditions, especially for vegetables such as lettuce. We previously showed that illumination by a combination of red, blue, and white LEDs with a high red light intensity, was optimal for lettuce cultivation; however, the effect of the photoperiod on lettuce cultivation was not investigated. In the current work, we investigated the influence of photoperiod on production (total biomass and dry weight) and parameters of photosynthesis, respiration rate, and relative chlorophyll content in lettuce plants. A 16 h (light):8 h (dark) illumination regime was used as the control. In this work, we investigated the effect of photoperiod on total biomass and dry weight production in lettuce plants as well as on photosynthesis, respiration rate and chlorophyll content. A lighting regime 16:8 h (light:dark) was used as control. A shorter photoperiod (8 h) decreased total biomass and dry weight in lettuce, and this effect was related to the suppression of the linear electron flow caused by the decreasing content of chlorophylls and, therefore, light absorption. A longer photoperiod (24 h) increased the total biomass and dry weight, nevertheless an increase in photosynthetic processes, light absorption by leaves and chlorophyll content was not recorded, nor were differences in respiration rate, thus indicating that changes in photosynthesis and respiration are not necessary conditions for stimulating plant production. A simple model to predict plant production was also developed to address the question of whether increasing the duration of illumination stimulates plant production without inducing changes in photosynthesis and respiration. Our results indicate that increasing the duration of illumination can stimulate dry weight accumulation and that this effect can also be induced using the equal total light integrals for day (i.e., this stimulation can be also caused by increasing the light period while decreasing light intensity). Increasing the duration of illumination is therefore an effective approach to stimulating lettuce production under artificial lighting.

How plants synthesize coenzyme Q

Coenzyme Q (CoQ) is a conserved redox-active lipid that has a wide distribution across the domains of life. CoQ plays a key role in the oxidative electron transfer chain and serves as a crucial antioxidant in cellular membranes. Our understanding of CoQ biosynthesis in eukaryotes has come mostly from studies of yeast. Recently, significant advances have been made in understanding CoQ biosynthesis in plants. Unique mitochondrial flavin-dependent monooxygenase and benzenoid ring precursor biosynthetic pathways have been discovered, providing new insights into the diversity of CoQ biosynthetic pathways and the evolution of phototrophic eukaryotes. We summarize research progress on CoQ biosynthesis and regulation in plants and recent efforts to increase the CoQ content in plant foods.

Uptake of Pharmaceutical Pollutants and Their Metabolites from Soil Fertilized with Manure to Parsley Tissues

Manure is a major source of soil and plant contamination with veterinary drugs residues. The aim of this study was to evaluate the uptake of 14 veterinary pharmaceuticals by parsley from soil fertilized with manure. Pharmaceutical content was determined in roots and leaves. Liquid chromatography coupled with tandem mass spectrometry was used for targeted analysis. Screening analysis was performed to identify transformation products in the parsley tissues. A solid-liquid extraction procedure was developed combined with solid-phase extraction, providing recoveries of 61.9–97.1% for leaves and 51.7–95.6% for roots. Four analytes were detected in parsley: enrofloxacin, tylosin, sulfamethoxazole, and doxycycline. Enrofloxacin was detected at the highest concentrations (13.4–26.3 ng g⁻¹). Doxycycline accumulated mainly in the roots, tylosin in the leaves, and sulfamethoxazole was found in both tissues. 14 transformation products were identified and their distribution were determined. This study provides important data on the uptake and transformation of pharmaceuticals in plant tissues.

Predictive metabolomics of multiple Atacama plant species unveils a core set of generic metabolites for extreme climate resilience

Current crop yield of the best ideotypes is stagnating and threatened by climate change. In this scenario, understanding wild plant adaptations in extreme ecosystems offers an opportunity to learn about new mechanisms for resilience. Previous studies have shown species specificity for metabolites involved in plant adaptation to harsh environments. Here, we combined multispecies ecological metabolomics and machine learning-based generalized linear model predictions to link the metabolome to the plant environment in a set of 24 species belonging to 14 families growing along an altitudinal gradient in the Atacama Desert. Thirty-nine common compounds predicted the plant environment with 79% accuracy, thus establishing the plant metabolome as an excellent integrative predictor of environmental fluctuations. These metabolites were independent of the species and validated both statistically and biologically using an independent dataset from a different sampling year. Thereafter, using multiblock predictive regressions, metabolites were linked to climatic and edaphic stressors such as freezing temperature, water deficit and high solar irradiance. These findings indicate that plants from different evolutionary trajectories use a generic metabolic toolkit to face extreme environments. These core metabolites, also present in agronomic species, provide a unique metabolic goldmine for improving crop performances under abiotic pressure.

Between Light and Shading: Morphological, Biochemical, and Metabolomics Insights Into the Influence of Blue Photoselective Shading on Vegetable Seedlings

High nursery densities reduce the seedling quality due to the competition for light. High light intensity, shading, and blue light depletion activate morphophysiological and metabolomic responses in plants, resulting in size modification to gain an advantage over neighboring plants. Our research aimed to unravel the effects of light intensity and quality on nursery seedlings at the morphological and biochemical levels. To this aim, the effect of black shading and blue photoselective shading nets were investigated in terms of morphometric, ionomic, and untargeted metabolomics signatures in Cucurbita pepo L., Citrullus lanatus L., Solanum lycopersicum L., and Solanum melongena L. seedlings. Plant height, diameter, sturdiness index, leaf area, specific leaf area, shoot/root ratio, and mineral content (by ion chromatography-IC) were evaluated. In C. pepo L and C. lanatus L., the blue net reduced the shoot/root and chlorophyll a/b ratios and increased stem diameter and total chlorophyll content. The black net increased plant height, stem diameter, and sturdiness index in Solanum lycopersicum L. and Solanum melongena L. At the same time, unshading conditions reduced leaf area, specific leaf area, shoot/root ratio, and total chlorophyll content. The blue net improved the sturdiness index and quality of C. pepo L. and C. lanatus L. Such impact on morphological parameters induced by the different shading conditions was corroborated by a significant modulation at the metabolomics level. Untargeted metabolomic phytochemical signatures of the selected plants, and the subsequent multivariate analysis coupled to pathway analysis, allowed highlighting a broad and diverse biochemical modulation. Metabolomics revealed that both primary and secondary metabolism were largely affected by the different shading conditions, regardless of the species considered. A common pattern arose to point at the activation of plant energy metabolism and lipid biosynthesis, together with a generalized down accumulation of several secondary metabolites, particularly phenylpropanoids. Our findings indicate an intriguing scientific interest in the effects of selective shading and its application to other species and different phenological stages.

Role of Circadian Rhythms in Major Plant Metabolic and Signaling Pathways

Plants require an endogenous regulatory network and mechanism to cope with diurnal environmental changes and compensate for their sessile nature. Plants use the circadian clock to anticipate diurnal changes. Circadian rhythm predicts a 24-h cycle with 16 h of light and 8 h of darkness in response to abiotic and biotic factors as well as the appropriate temperature. For a plant's fitness, proper growth, and development, these rhythms synchronize the diurnal photoperiodic changes. Input pathway, central oscillator, and output pathway are the three components that make up the endogenous clock. There are also transcriptional and translational feedback loops (TTFLs) in the clock, which are dependent on the results of gene expression. Several physiological processes, such as stress acclimatization, hormone signaling, morphogenesis, carbon metabolism, and defense response, are currently being investigated for their interactions with the circadian clock using phenotypic, genomic, and metabolic studies. This review examines the role of circadian rhythms in the regulation of plant metabolic pathways, such as photosynthesis and carbon metabolism, as well as developmental and degenerative processes, such as flowering and senescence. Furthermore, we summarized signaling pathways related to circadian rhythms, such as defense response and gene regulatory pathways.

SlWRKY35 positively regulates carotenoid biosynthesis by activating the MEP pathway in tomato fruit

Carotenoids are vital phytonutrients widely recognised for their health benefits. Therefore, it is vital to thoroughly investigate the metabolic regulatory network underlying carotenoid biosynthesis and accumulation to open new leads towards improving their contents in vegetables and crops. The outcome of our study defines SlWRKY35 as a positive regulator of carotenoid biosynthesis in tomato. SlWRKY35 can directly activate the expression of the 1-deoxy-d-xylulose 5-phosphate synthase (SlDXS1) gene to reprogramme metabolism towards the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway, leading to enhanced carotenoid accumulation. We also show that the master regulator SlRIN directly regulates the expression of SlWRKY35 during tomato fruit ripening. Compared with the SlLCYE overexpression lines, coexpression of SlWRKY35 and SlLCYE can further enhance lutein production in transgenic tomato fruit, indicating that SlWRKY35 represents a potential target towards designing innovative metabolic engineering strategies for carotenoid derivatives. In addition to providing new insights into the metabolic regulatory network associated with tomato fruit ripening, our data define a new tool for improving fruit content in specific carotenoid compounds.

ODORANT1 targets multiple metabolic networks in petunia flowers

Scent bouquets produced by the flowers of Petunia spp. (petunia) are composed of a complex mixture of floral volatile benzenoid and phenylpropanoid compounds (FVBPs), which are specialized metabolites derived from phenylalanine (Phe) through an interconnected network of enzymes. The biosynthesis and emission of high levels of these volatiles requires coordinated transcriptional activation of both primary and specialized metabolic networks. The petunia R2R3-MYB transcription factor ODORANT 1 (ODO1) was identified as a master regulator of FVBP production and emission; however, our knowledge of the direct regulatory targets of ODO1 has remained limited. Using chromatin immunoprecipitation followed by sequencing (ChIP-seq) in petunia flowers, we identify genome-wide ODO1-bound genes that are enriched not only in genes involved in the biosynthesis of the Phe precursor, as previously reported, but also genes associated with the specialized metabolic pathways involved in generating phenylpropanoid intermediates for FVBPs. ODO1-bound genes are also involved in methionine and S-adenosylmethionine metabolism, which could modulate methyl group supplies for certain FVBPs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and RNA-seq analysis in an ODO1 RNAi knockdown line revealed that ODO1-bound targets are expressed at lower levels when ODO1 is suppressed. A cis-regulatory motif, CACCAACCCC, was identified as a potential binding site for ODO1 in the promoters of genes that are both bound and activated by ODO1, which was validated by in planta promoter reporter assays with wild-type and mutated promoters. Overall, our work presents a mechanistic model for ODO1 controlling an extensive gene regulatory network that contributes to FVBP production to give rise to floral scent.

Root exudation of prometryn and its metabolites from Chinese celery (Apium graveolens)

Root exudates from Chinese celery (Apium graveolens) and Chinese cabbage (pak choi, Brassica chinensis) plants treated by prometryn, an herbicide, were qualitatively and quantitatively investigated and compared under hydroponic cultivation. Prometryn and its metabolites released into the nutrient solution were analyzed by ultra-performance liquid chromatograph coupled with orbitrap mass spectrometer to investigate whether this xylem-mobile herbicide is exuded from the roots. The results showed that celery and pak choi had different root exudation profiles. Celery metabolized prometryn to prometryn sulfoxide and released both compounds from the roots. In contrast, pak choi barely metabolized or actively released prometryn from the roots. The concentration of prometryn sulfoxide released from celery after 96 hr was 21 µg/L, which was nearly one-third that of released prometryn. Our results indicate that the root exudation and translocation of xylem-mobile herbicides could be significant in plants and are highly species dependent compared with phloem-mobile herbicides.

The Native Arbuscular Mycorrhizal Fungi and Vermicompost-Based Organic Amendments Enhance Soil Fertility, Growth Performance, and the Drought Stress Tolerance of Quinoa

The present study aimed to determine the effects of biostimulants on the physicochemical parameters of the agricultural soil of quinoa under two water regimes and to understand the mode of action of the biostimulants on quinoa for drought adaptation. We investigated the impact of two doses of vermicompost (5 and 10 t/ha) and arbuscular mycorrhizal fungi applied individually, or in joint application, on attenuating the negative impacts of water shortage and improving the agro-physiological and biochemical traits of quinoa, as well as soil fertility, under two water regimes (well-watered and drought stress) in open field conditions. Exposure to drought decreased biomass, leaf water potential, and stomatal conductance, and increased malondialdehyde and hydrogen peroxide content. Mycorrhiza and/or vermicompost promoted plant growth by activating photosynthesis machinery and nutrient assimilation, leading to increased total soluble sugars, proteins, and antioxidant enzyme activities in the leaf and root. After the experiment, the soil's total organic matter, phosphorus, nitrogen, calcium, and soil glomalin content improved by the single or combined application of mycorrhiza and vermicompost. This knowledge suggests that the combination of mycorrhiza and vermicompost regulates the physiological and biochemical processes employed by quinoa in coping with drought and improves the understanding of soil-plant interaction.

Comprehensive Profiling of Paper Mulberry (Broussonetia papyrifera) Crotonylome Reveals the Significance of Lysine Crotonylation in Young Leaves

Lysine crotonylation is a newly discovered and reversible posttranslational modification involved in various biological processes, especially metabolism regulation. A total of 5159 lysine crotonylation sites in 2272 protein groups were identified. Twenty-seven motifs were found to be the preferred amino acid sequences for crotonylation sites. Functional annotation analyses revealed that most crotonylated proteins play important roles in metabolic processes and photosynthesis. Bioinformatics analysis suggested that lysine crotonylation preferentially targets a variety of important biological processes, including ribosome, glyoxylate and dicarboxylate metabolism, carbon fixation in photosynthetic organisms, proteasome and the TCA cycle, indicating lysine crotonylation is involved in the common mechanism of metabolic regulation. A protein interaction network analysis revealed that diverse interactions are modulated by protein crotonylation. These results suggest that lysine crotonylation is involved in a variety of biological processes. HSP70 is a crucial protein involved in protecting plant cells and tissues from thermal or abiotic stress responses, and HSP70 protein was found to be crotonylated in paper mulberry. This systematic analysis provides the first comprehensive analysis of lysine crotonylation in paper mulberry and provides important resources for further study on the regulatory mechanism and function of the lysine crotonylated proteome.

Study the Effect of P. minor Seaweed Crude Extract as a Biostimulant on Soybean

<b>Background and Objective:</b> Seaweed biostimulants are often used in agriculture because of their benefits in increasing growth, production and quality of plants and are safe for the environment. <i>Padina minor</i> is one of the potential seaweeds that contains high macro and micronutrients and has also been shown to increase the vegetative growth of several plants. This study aims to determine the effect of <i>P. minor</i> seaweed extract in various concentrations and frequencies as a biostimulant on the growth and production of soybean plants. <b>Materials and Methods:</b> <i>Padina minor</i> extract was applied to soybean plants with several concentrations (0, 10, 20, 30 and 40%) at three different application times. Where 1 application (2 weeks after planting), 2 applications (2 and 4 weeks after planting) and 3 applications (2, 4 and 5 weeks after planting). <b>Results:</b> <i>Padina minor</i> extract with a concentration of 40% with 1 application was able to increase plant height and shorten soybean harvest life. While the <i>P. minor</i> extract with a concentration of 40% with two and three applications was able to increase the gross and dry weight of plants, the number of pods, gross and dry mass of whole seeds. <b>Conclusion:</b> <i>Padina minor</i> seaweed extract with a concentration of 40% was able to increase the growth and production of soybean plants.

Plant Copper Metalloenzymes As Prospects for New Metabolism Involving Aromatic Compounds

Copper is an important transition metal cofactor in plant metabolism, which enables diverse biocatalysis in aerobic environments. Multiple classes of plant metalloenzymes evolved and underwent genetic expansions during the evolution of terrestrial plants and, to date, several representatives of these copper enzyme classes have characterized mechanisms. In this review, we give an updated overview of chemistry, structure, mechanism, function and phylogenetic distribution of plant copper metalloenzymes with an emphasis on biosynthesis of aromatic compounds such as phenylpropanoids (lignin, lignan, flavonoids) and cyclic peptides with macrocyclizations via aromatic amino acids. We also review a recent addition to plant copper enzymology in a copper-dependent peptide cyclase called the BURP domain. Given growing plant genetic resources, a large pool of copper biocatalysts remains to be characterized from plants as plant genomes contain on average more than 70 copper enzyme genes. A major challenge in characterization of copper biocatalysts from plant genomes is the identification of endogenous substrates and catalyzed reactions. We highlight some recent and future trends in filling these knowledge gaps in plant metabolism and the potential for genomic discovery of copper-based enzymology from plants.

A dedicated flavin-dependent monooxygenase catalyzes the hydroxylation of demethoxyubiquinone into ubiquinone (coenzyme Q) in Arabidopsis

Ubiquinone (Coenzyme Q) is a vital respiratory cofactor and liposoluble antioxidant. In plants, it is not known how the C-6 hydroxylation of demethoxyubiquinone, the penultimate step in ubiquinone biosynthesis, is catalyzed. The combination of cross-species gene network modeling along with mining of embryo-defective mutant databases of Arabidopsis thaliana identified the embryo lethal locus EMB2421 (At1g24340) as a top candidate for the missing plant demethoxyubiquinone hydroxylase. In marked contrast with prototypical eukaryotic demethoxyubiquinone hydroxylases, the catalytic mechanism of which depends on a carboxylate-bridged di-iron domain, At1g24340 is homologous to FAD-dependent oxidoreductases that instead use NAD(P)H as an electron donor. Complementation assays in Saccharomyces cerevisiae and Escherichia coli demonstrated that At1g24340 encodes a functional demethoxyubiquinone hydroxylase and that the enzyme displays strict specificity for the C-6 position of the benzoquinone ring. Laser-scanning confocal microscopy also showed that GFP-tagged At1g24340 is targeted to mitochondria. Silencing of At1g24340 resulted in 40 to 74% decrease in ubiquinone content and de novo ubiquinone biosynthesis. Consistent with the role of At1g24340 as a benzenoid ring modification enzyme, this metabolic blockage could not be bypassed by supplementation with 4-hydroxybenzoate, the immediate precursor of ubiquinone's ring. Unlike in yeast, in Arabidopsis overexpression of demethoxyubiquinone hydroxylase did not boost ubiquinone content. Phylogenetic reconstructions indicated that plant demethoxyubiquinone hydroxylase is most closely related to prokaryotic monooxygenases that act on halogenated aromatics and likely descends from an event of horizontal gene transfer between a green alga and a bacterium.

FT-ICR-MS-based metabolomics: A deep dive into plant metabolism

Metabolomics involves the identification and quantification of metabolites to unravel the chemical footprints behind cellular regulatory processes and to decipher metabolic networks, opening new insights to understand the correlation between genes and metabolites. In plants, it is estimated the existence of hundreds of thousands of metabolites and the majority is still unknown. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is a powerful analytical technique to tackle such challenges. The resolving power and sensitivity of this ultrahigh mass accuracy mass analyzer is such that a complex mixture, such as plant extracts, can be analyzed and thousands of metabolite signals can be detected simultaneously and distinguished based on the naturally abundant elemental isotopes. In this review, FT-ICR-MS-based plant metabolomics studies are described, emphasizing FT-ICR-MS increasing applications in plant science through targeted and untargeted approaches, allowing for a better understanding of plant development, responses to biotic and abiotic stresses, and the discovery of new natural nutraceutical compounds. Improved metabolite extraction protocols compatible with FT-ICR-MS, metabolite analysis methods and metabolite identification platforms are also explored as well as new in silico approaches. Most recent advances in MS imaging are also discussed.

A novel bivalent chromatin associates with rapid induction of camalexin biosynthesis genes in response to a pathogen signal in Arabidopsis

Temporal dynamics of gene expression underpin responses to internal and environmental stimuli. In eukaryotes, regulation of gene induction includes changing chromatin states at target genes and recruiting the transcriptional machinery that includes transcription factors. As one of the most potent defense compounds in Arabidopsis thaliana, camalexin can be rapidly induced by bacterial and fungal infections. Though several transcription factors controlling camalexin biosynthesis genes have been characterized, how the rapid activation of genes in this pathway upon a pathogen signal is enabled remains unknown. By combining publicly available epigenomic data with in vivo chromatin modification mapping, we found that camalexin biosynthesis genes are marked with two epigenetic modifications with opposite effects on gene expression, trimethylation of lysine 27 of histone 3 (H3K27me3) (repression) and acetylation of lysine 18 of histone 3 (H3K18ac) (activation), to form a previously uncharacterized type of bivalent chromatin. Mutants with reduced H3K27me3 or H3K18ac suggested that both modifications were required to determine the timing of gene expression and metabolite accumulation at an early stage of the stress response. Our study indicates that the H3K27me3-H3K18ac bivalent chromatin, which we name as kairostat, plays an important role in controlling the timely induction of gene expression upon stress stimuli in plants.

Plant cytochrome P450 plasticity and evolution

The superfamily of cytochrome P450 (CYP) enzymes plays key roles in plant evolution and metabolic diversification. This review provides a status on the CYP landscape within green algae and land plants. The 11 conserved CYP clans known from vascular plants are all present in green algae and several green algae-specific clans are recognized. Clan 71, 72, and 85 remain the largest CYP clans and include many taxa-specific CYP (sub)families reflecting emergence of linage-specific pathways. Molecular features and dynamics of CYP plasticity and evolution are discussed and exemplified by selected biosynthetic pathways. High substrate promiscuity is commonly observed for CYPs from large families, favoring retention of gene duplicates and neofunctionalization, thus seeding acquisition of new functions. Elucidation of biosynthetic pathways producing metabolites with sporadic distribution across plant phylogeny reveals multiple examples of convergent evolution where CYPs have been independently recruited from the same or different CYP families, to adapt to similar environmental challenges or ecological niches. Sometimes only a single or a few mutations are required for functional interconversion. A compilation of functionally characterized plant CYPs is provided online through the Plant P450 Database (erda.dk/public/vgrid/PlantP450/).

Phylogenetic history of vascular plant metabolism revealed using a macroevolutionary common garden

While the fundamental biophysics of C3 photosynthesis is highly conserved across plants, substantial leaf structural and enzymatic variation translates into variability in rates of carbon assimilation. Although this variation is well documented, it remains poorly understood how photosynthetic rates evolve, and whether macroevolutionary changes are related to the evolution of leaf morphology and biochemistry. A substantial challenge in large-scale comparative studies is disentangling evolutionary adaptation from environmental acclimation. We overcome this by using a 'macroevolutionary common garden' approach in which we measured metabolic traits (Jmax and Vcmax) from 111 phylogenetically diverse species in a shared environment. We find substantial phylogenetic signal in these traits at moderate phylogenetic timescales, but this signal dissipates quickly at deeper scales. Morphological traits exhibit phylogenetic signal over much deeper timescales, suggesting that these are less evolutionarily constrained than metabolic traits. Furthermore, while morphological and biochemical traits (LMA, Narea and Carea) are weakly predictive of Jmax and Vcmax, evolutionary changes in these traits are mostly decoupled from changes in metabolic traits. This lack of tight evolutionary coupling implies that it may be incorrect to use changes in these functional traits in response to global change to infer that photosynthetic strategy is also evolving.

Photosynthetic Responses of Anthurium × 'Red' under Different Light Conditions

Light is an essential energy source for plant photosynthesis, although it can also be a stress-causing element. Therefore, the current research was aimed to compare photosynthetic responses of Anthurium × 'Red' leaves at different positions (bottom old leaf, 1; center mature leaf, 2; top expanded leaf, 3) established under three photosynthetic photon flux densities (PPFDs): 550 μmol·m^-2·s^-1 as high (H), 350 μmol·m^-2·s^-1 as medium (M), and 255 μmol·m^-2·s^-1 as low (L). After six months, all the replicates were relocated to interior rooms with a PPFD of 30 μmol·m^-2·s^-1. There were no significant differences in chlorophyll concentration of the old leaf among treatments, before (Day 0) and after shifting the plants to interior rooms (Day 30). The total chlorophyll concentrations of the mature and top leaves increased significantly. In greenhouse conditions, H and M treatments did not show any significant change for net photosynthetic rate (Pn) at various leaf positions. However, M2 exhibited an improved Pn in the interior conditions. Plants grown under M treatment were greener and had bigger leaves compared to other treatments. Our study reveals that Anthurium × 'Red' photosynthesis responses to different light conditions varied distinctly. However, M treatment can keep the plants looking green by accumulating enough energy for indoor conditions, and middle and lower leaves may be triggered to restore photosynthetic activity under low light or indoor conditions.

Fine mapping identifies NAD-ME1 as a candidate underlying a major locus controlling temporal variation in primary and specialized metabolism in Arabidopsis

Plant metabolism is modulated by a complex interplay between internal signals and external cues. A major goal of all quantitative metabolomic studies is to clone the underlying genes to understand the mechanistic basis of this variation. Using fine-scale genetic mapping, in this work we report the identification and initial characterization of NAD-DEPENDENT MALIC ENZYME 1 (NAD-ME1) as the candidate gene underlying the pleiotropic network Met.II.15 quantitative trait locus controlling variation in plant metabolism and circadian clock outputs in the Bay × Sha Arabidopsis population. Transcript abundance and promoter analysis in NAD-ME1^Bay-0 and NAD-ME1^Sha alleles confirmed allele-specific expression that appears to be due a polymorphism disrupting a putative circadian cis-element binding site. Analysis of transfer DNA insertion lines and heterogeneous inbred families showed that transcript variation of the NAD-ME1 gene led to temporal shifts of tricarboxylic acid cycle intermediates, glucosinolate (GSL) accumulation, and altered regulation of several GSL biosynthesis pathway genes. Untargeted metabolomic analyses revealed complex regulatory networks of NAD-ME1 dependent upon the daytime. The mutant led to shifts in plant primary metabolites, cell wall components, isoprenoids, fatty acids, and plant immunity phytochemicals, among others. Our findings suggest that NAD-ME1 may act as a key gene to coordinate plant primary and secondary metabolism in a time-dependent manner.

Evaluation of Callus Cultures to Elucidate the Metabolism of Tebuconazole, Flurtamone, Fenhexamid, and Metalaxyl-M in Brassica napus L., Glycine max (L.) Merr., Zea mays L., and Triticum aestivum L

Plant cell cultures can be used to identify the metabolic degradation of pesticides in crops. Therefore, Brassica napus L., Glycine max (L.) Merr., Zea mays L. and Triticum aestivum L. were used to elucidate the metabolic degradation of the following pesticides: tebuconazole, flurtamone, fenhexamid, and metalaxyl-M. Callus cultures were treated with 10 μM of the named pesticides by passive diffusion out of the nutrition agar while young plants were hydroponically exposed to it. After 14 days, the comparison of in planta and in vitro experiments showed that the metabolic degradation is well described by in vitro callus cultures. The intracellular uptake of all pesticides and a broad spectrum of exemplarily hydroxylated and conjugated metabolites were detectable. Overall, the comparability of the nature of residues out of both experiments with the regulatory guideline metabolism studies could be demonstrated. Therefore, we recommend it as a potential screening tool to elucidate the metabolism of pesticides in crops.

Novel Insights into the Effect of Pythium Strains on Rapeseed Metabolism

Pythium oligandrum is a unique biological control agent. This soil oomycete not only acts as a mycoparasite, but also interacts with plant roots and stimulates plant defense response via specific elicitors. In addition, P. oligandrum can synthetize auxin precursors and stimulate plant growth. We analyzed the secretomes and biochemical properties of eleven Pythium isolates to find a novel and effective strain with advantageous features for plants. Our results showed that even closely related P. oligandrum isolates significantly differ in the content of compounds secreted into the medium, and that all strains secrete proteins, amino acids, tryptamine, phenolics, and hydrolytic enzymes capable of degrading cell walls (endo-β-1,3-glucanase, chitinase, and cellulase), exoglycosidases (especially β-glucosidase), proteases, and phosphatases. The most different strain was identified as a not yet described Pythium species. The changes in metabolism of Brassica napus plants grown from seeds coated with the tested Pythium spp. were characterized. Enhanced levels of jasmonates, ethylene precursor, and salicylic acid may indicate better resistance to a wide variety of pathogens. Glucosinolates, as defense compounds against insects and herbivores, were enhanced in young plants. Altogether, P. oligandrum strains varied in their life strategies, and either they could perform equally as plant growth promoters and mycoparasites or they had developed one of these strategies better.

Characterization of In Vivo Function(s) of Members of the Plant Mitochondrial Carrier Family

Although structurally related, mitochondrial carrier family (MCF) proteins catalyze the specific transport of a range of diverse substrates including nucleotides, amino acids, dicarboxylates, tricarboxylates, cofactors, vitamins, phosphate and H⁺. Despite their name, they do not, however, always localize to the mitochondria, with plasma membrane, peroxisomal, chloroplast and thylakoid and endoplasmic reticulum localizations also being reported. The existence of plastid-specific MCF proteins is suggestive that the evolution of these proteins occurred after the separation of the green lineage. That said, plant-specific MCF proteins are not all plastid-localized, with members also situated at the endoplasmic reticulum and plasma membrane. While by no means yet comprehensive, the in vivo function of a wide range of these transporters is carried out here, and we discuss the employment of genetic variants of the MCF as a means to provide insight into their in vivo function complementary to that obtained from studies following their reconstitution into liposomes.

Metabolism of esfenvalerate in tomato plants (Solanum lycopersicum)

The metabolic fate of esfenvalerate (1), ¹⁴C-labeled at the chlorophenyl or phenoxyphenyl ring, in tomato plants was investigated by spraying it three times at 15 g/ha. The overall metabolic trend of 1 was similar in foliage and fruit. The applied 1 gradually penetrated into the foliage/fruit, and approximately 30% of the total radioactive residue (TRR) distributed within the plant. The applied radioactivity remained mostly intact on the plant surface, while its degradation proceeded via ester cleavage to produce two corresponding acids derived from the chlorophenyl and phenoxyphenyl moieties, followed by saccharide conjugation at the inner tissues (each <5%TRR). While 1 retained its optical configuration (2S,αS) on the plant surface and in the fruit, a very slight isomerization at the α-cyanobenzyl carbon occurred to form a (2S,αR) isomer in the foliage (≤1%TRR). The isomerization at another asymmetric carbon C2 in the isovaleric acid moiety did not proceed on/in the plant for 1 or its metabolite.

Climate change shapes the future evolution of plant metabolism

Planet Earth has experienced many dramatic atmospheric and climatic changes throughout its 4.5-billion-year history that have profoundly impacted the evolution of life as we know it. Photosynthetic organisms, and specifically plants, have played a paramount role in shaping the Earth's atmosphere through oxygen production and carbon sequestration. In turn, the diversity of plants has been shaped by historical atmospheric and climatic changes: plants rose to this challenge by evolving new developmental and metabolic traits. These adaptive traits help plants to thrive in diverse growth conditions, while benefiting humanity through the production of food, raw materials, and medicines. However, the current rapid rate of climate change caused by human activities presents unprecedented new challenges to the future of plants. Here, we discuss the potential effects of modern climate change on plants, with specific attention to plant specialized metabolism. We explore potential avenues of future scientific investigations, powered by cutting-edge methods such as synthetic biology and genome engineering, to better understand and mitigate the consequences of rapid climate change on plant fitness and plant usage by humans.